Then invention related generally to aircraft guidance systems, and more particularly to a guidance display that uses a predictive flight path, or performance, symbology set.
In order to reduce tracking errors and pilot workload, a pilot must be provided with increased situational awareness of an aircraft the pilot is flying with respect to a desired flight path. Additionally the pilot must be aware of the actual aircraft performance, or flight path vector (FPV), the desired, or commanded, aircraft performance, and the predicted aircraft performance. The use of a perspective display with a predictive flight path, or performance, symbology set provides increased situational awareness. Perspective displays with predictive symbology permit a pilot to xe2x80x9cseexe2x80x9d what will be required, or demanded, of the aircraft to maintain a desired flight path, as well as where the aircraft will be in a finite period of time. With the increased situational awareness, the pilot""s workload is lower, thereby permitting better flight management.
Flight director guidance for critical maneuvers, such as those maneuvers with very small, or reduced, margins for error, is essential for precision navigation requirements. Known guidance symbology, such as Delta-Veebar and Two-Bar, work well, but are limited in their ability to display future flight path information to the pilot and/or the results of pilot control input. Both Delta-Veebar and Two-Bar guidance symbology are based on compensatory tracking tasks.
The traditional symbology used for instrument approaches in vertical flight aircraft, such as rotorcraft or tiltrotors, is based on compensatory tracking tasks. Compensatory tracking tasks are derived by monitoring actual aircraft attitude against commanded attitude during flight, and actual cross-track error against commanded cross-track during flight. Guidance errors are generally computed as the difference between guidance commands and sensed aircraft state. The errors are sent to flight director algorithms, which generate steering commands. These commands appear as flight director symbology on a cockpit display and direct the pilot where to position the lateral stick (roll), thrust control lever (power), and the longitudinal stick (pitch). If the pilot responds with the appropriate control inputs to satisfy the flight director steering commands, the aircraft will converge on the reference values selected.
Symbology based on compensatory tracking tasks, are designed to provide a pilot with command guidance instructing a pilot to make flight adjustments to guide an aircraft from an off-course situation to return to a nominal, or null error, solution. Compensatory tracking does not provide the pilot with information indicating how far off course the plane is, nor what flight control input is required to regain course centerline. Therefore, the pilot must constantly monitor command and the results of control inputs. Furthermore, compensatory tracking does not provide flight path predictability, and displays that utilize compensatory symbology require much cognitive processing by the pilot and cause heavy pilot mental workload leading to errors, especially in high workload constrained terminal areas, or during low altitude operations. For example, excessive pilot mental workload can lead to full-scale deflection errors, or total loss of situational control resulting in a maximum deviation mandated missed approach. Thus, compensatory symbology often creates display clutter and high pilot cognitive workload, which increases the risk of flight technical errors (FTE""s).
To overcome the shortcomings of symbology based on compensatory tracking tasks, perspective display sets, or three-dimensional (3D) displays, have been developed to some degree with varying symbology. Most perspective display sets have been 3D tunnels, consisting of a series of rectangles connected by lines through the corners.
More recent pathway xe2x80x9ctunnelxe2x80x9d designs have produced four-dimensional capabilities where the guidance is a pathway produced by four perspective lines through the corners of a command plane, into which a flight path vector (FPV) symbol is placed.
These perspective symbology sets accomplish their intended tasks, but nevertheless result in additional display clutter. Therefore, it is desirable to develop a perspective display set that yields the same, or better, performance results as current perspective symbology sets, but causes less display clutter, reduces pilot work load, and reduces FTE""s.
In one preferred embodiment, a predictive flight path symbology system is provided for increasing pilot situational awareness of an aircraft. The system includes a pilot display, and a precision pathway flight guidance (PPFG) symbology set displayed on the pilot display. The PPFG symbology set includes broken line symbols representing an open guidance tunnel and providing flow field data, a half-bracket symbol to indicate that the aircraft is no longer in the open tunnel represented by the broken line symbols and the direction to turn to re-intercept the guidance tunnel, and a quickened flight path vector (QFPV) symbol to provide the pilot with predictive flight path information.
In another embodiment, a method is provided for increasing pilot situational awareness of an aircraft utilizing a predictive flight path symbology set. The method includes utilizing an open tunnel bounded by broken lines symbol to provide flow field data, utilizing a half-bracket symbol to indicate that the aircraft is no longer in a tunnel, and utilizing a quickened flight path vector (QFPV) symbol to provide the pilot with predictive flight path information.
In yet another embodiment, a precision pathway flight guidance (PPFG) symbology set is provided for increasing pilot situational awareness of an aircraft. The PPFG symbology set includes broken line symbols representing an open tunnel and providing flow field data, a half-bracket symbol to indicate that the aircraft is no longer in the open tunnel represented by the broken line symbols, and a quickened flight path vector (QFPV) symbol to provide the pilot with predictive flight path information. The PPFG symbology set further includes a quickened command reference frame configured to indicate a commanded location in which the pilot is to locate the QFPV in order to satisfy on-course tracking requirements, a longitudinal pitch trim symbol configured to maintain a desired pitch of the aircraft by the pilot adjusting the trim of the aircraft to align the longitudinal pitch trim symbol with the QFPV, and a power trim symbol configured to maintain a desired trim of the aircraft by the pilot adjusting power of the aircraft in order to position the power trim symbol level the QFPV.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.